Samspade ,
Here are some loads that I use in my .243 AI which should serve as suitable starting loads for your 6mm/284 which has more case capacity .
46.5 gns AR 2208 (Varget in the USA) with 55gn Nosler BT gives me 4030 FPS and is my most accurate load . 5 shots in the 3's .I can get up to 4200 fps without pressure signs with 48.5 gns AR 2208 .
42.5 gns AR 2208 / Varget with 70 gn Nosler BT . This gives about 3550 fps and I use for fireforming . I can get to 3700 FPS safely .My manual lists 42 gns as maximum in the 6mm/284 with 70 gn projectile which I can't work out .
42 gns AR 2208 / Varget with 75 gn V Max for 3520 FPS . Mild but accurate in my rifle .
49 gns WXR with 87 gn V Max . WXR is I believe same as RL 22 but sold by Winchester .This is maximum in my rifle but 50 gns listed as a starter for 6mm/284 in my loading manual . .
Have tried other powders but these 2 work well and give good velocity / accuracy . Suggest Varget will be hard to beat for projectiles up to 75 gns .
My loading manual suggests AR 2213 SC (sold in USA as H4831 SC) is THE powder for the 6mm/284 .
Starting loads :- 54 gns with 60 gn projectile , 53 gns with 65 gn projectile , 52 gns with 70 gn and 75 gn projectile ,49 gns with 87 gn projectile .
Maximum loads for AR 2213 SC are up about 6 - 8% on those listed above
Good luck . [img]/ubbthreads/images/graemlins/smile.gif[/img]

I've got one with a 1/14twist barrel and have only used 68br bullets. I use is H-4831 good place to start is 52 to 56grs. I know Hogdon has loading on the 6x284 may want to look them up on the net. Well good luck.

For bullets 80 grains or more I would use R-22 or IMR-4831, IMR-7828. I would start at 50 grains and work up from there. For bullets less then 80 grains I would use IMR-4350 R-19 or Varget. I would start at 45 grains and work up from there.